The invention relates to certain multidentate phosphite ligands, the catalyst compositions made therefrom and a catalytic hydrocyanation process which employs such multidentate phosphite ligands. In particular, the ligands have phenyl containing substituents attached to the ortho position of the terminal phenol group and/or attached to the ortho position of the backbone.
Phosphorus ligands are ubiquitous in catalysis and are used for a number of commercially important chemical transformations. Phosphorus ligands commonly encountered in catalysis include phosphines (A), and phosphites (B), shown below. In these representations, R can be virtually any organic group. Monophosphine and monophosphite ligands are compounds which contain a single phosphorus atom which serves as a donor to a metal. Bisphosphine, bisphosphite, and bis(phosphorus) ligands in general, contain two phosphorus donor atoms and normally form cyclic chelate structures with transition metals. 
There are several industrially important catalytic processes employing phosphorus ligands. For example, U.S. Pat. No. 5,910,600 to Urata, et al. discloses that bisphosphite compounds can be used as a constituting element of a homogeneous metal catalyst for various reactions such as hydrogenation, hydroformylation, hydrocyanation, hydrocarboxylation, hydroamidation, hydroesterification and aldol condensation.
Some of these catalytic processes are used in the commercial production of polymers, solvents, plasticizers and other commodity chemicals. Consequently, due to the extremely large worldwide chemical commodity market, even small incremental advances in yield or selectivity in any of these commercially important reactions are highly desirable. Furthermore, the discovery of certain ligands that may be useful for applications across a range of these commercially important reactions is also highly desirable not only for the commercial benefit, but also to enable consolidation and focusing of research and development efforts to a particular group of compounds.
U.S. Pat. No. 5,512,696 to Kreutzer, et al. discloses a hydrocyanation process using a multidentate phosphite ligand, and the patents and publications referenced therein describe hydrocyanation catalyst systems pertaining to the hydrocyanation of ethylenically unsaturated compounds. U.S. Pat. Nos. 5,723,641, 5,663,369, 5,688,986 and 5,847,191 disclose processes and catalyst compositions for the hydrocyanation of monoethylenically unsaturated compounds using zero-valent nickel and multidentate phosphite ligands, and Lewis acid promoters.
U.S. Pat. No. 5,821,378 to Foo, et al. discloses a liquid phase process for the hydrocyanation of diolefinic compounds to produce nonconjugated acyclic nitrites as well as a liquid phase process for the isomerization of those nitrites to 3- and/or 4-monoalkene linear nitriles where the reactions are carried out in the presence of zero-valent nickel and a multidentate phosphite ligand. Other catalytic processes for the hydrocyanation of olefins and the isomerization of monoalkene nitriles are described in the patents and publications referenced therein. Commonly assigned, published PCT Application WO99/06357 discloses multidentate phosphite ligands having alkyl ether substituents on the carbon attached to the ortho position of the terminal phenol group for use in a liquid phase process for the hydrocyanation of diolefinic compounds to produce nonconjugated acyclic nitrites as well as a liquid phase process for the isomerization of those nitrites to 3- and/or 4-monoalkene linear nitrites.
The use of multidentate phosphate ligands having binaphthalene and/or biphenyl bridging groups for hydroformylation reactions is disclosed in U.S. Pat. Nos. 5,235,113, 5,874,641, 5,710,344 and published PCT Application WO 97/33854
While the catalyst systems described above may represent commercially viable catalysts, it always remains desirable to provide even more effective, higher performing catalyst precursor compositions, catalytic compositions and catalytic processes to achieve full commercial potential for a desired reaction. The effectiveness and/or performance may be achieved in any or all of rapidity, selectivity, efficiency or stability, depending on the reaction performed. It is also desirable to provide such improved catalyst systems and/or processes which may be optimized for a commercially important reaction such hydrocyanation or isomerazation. Other objects and advantages of the present invention will become apparent to those skilled in the art upon reference to the detailed description which hereinafter follows.
The invention provides for a hydrocyanation process comprising reacting an acyclic, aliphatic, monoethylenicaly unsaturated compound in which the ethylenic double bond is not conjugated to any other olefinic group in the molecule with a source of HCN in the presence of a catalyst composition comprising a Lewis acid, a zero-valent nickel and at least one multidentate phosphite ligand selected from the group represented by the following formulae I II or III, in which all like reference characters have the same meaning, except as further explicitly limited. 
wherein
R1 is independently C1 to C18 primary or secondary alkyl;
R2 is independently aryl or substituted aryl;
R3 is independently aryl or substituted aryl;
R4 is independently C1 to C18 primary alkyl;
R5 is hydrogen;
R6 is independently aryl or substituted aryl;
R7 is independently C1 to C18 primary or secondary alkyl;
R8 is independently C1 to C18 primary or secondary alkyl; and
R9 is independently C1 to C18 primary or secondary alkyl;
wherein other positions on the aromatic rings may also be substituted with alkyl, ether or ester groups, or combinations of two or more thereof.
The invention also provides for a multidentate phosphite ligand having the structure represented by the following Formula I, II or III in which all like reference characters have the same meaning, except as further explicitly limited. 
wherein
R1 is independently C1 to C18 primary or secondary alkyl;
R2 is independently aryl or substituted aryl;
R3 is independently aryl or substituted aryl;
R4 is independently C1 to C18 primary alkyl;
R5 is hydrogen;
R6 is independently aryl or substituted aryl;
R7 is independently C1 to C18 primary or secondary alkyl;
R8 is independently C1 to C18 primary or secondary alkyl; and
R9 is independently C1 to C18 primary or secondary alkyl;
wherein other positions on the aromatic rings may also be substituted with alkyl, ether or ester groups, or combinations of two or more thereof.
The invention provides for certain multidentate phosphite ligands, improved catalyst systems employing such ligands, and the use of such multidentate phosphite ligands in hydrocyanation reactions.
The catalyst compositions useful in the invention preferably are comprised of a multidentate phosphite ligand of formula I, II and III and a transition metal. 
wherein
R1 is independently C1 to C18 primary alkyl;
R2 is independently aryl or substituted aryl;
R3 is independently aryl or substituted aryl;
R4 is independently C1 to C18 primary alkyl;
R5 is hydrogen;
R6 is independently aryl or substituted aryl;
R7 is independently C1 to C18 primary or secondary alkyl;
R8 is independently C1 to C18 primary or secondary alkyl; and
R9 is independently C1 to C18 primary or secondary alkyl;
wherein other positions on the aromatic rings may also be substituted with alkyl, ether or ester groups, or combinations of two or more thereof.
The divalent bridging compounds used in the ligands described in formulae I, II, and III may be prepared by a variety of methods known in the art. For example, 3,3xe2x80x2,5,5xe2x80x2-tetramethyl-2,2xe2x80x2-biphenol can be prepared according to J. Org. Chem., 1963, 28, 1063 and 3,3xe2x80x2,5,5xe2x80x2,6,6xe2x80x2-Hexamethyl-2,2xe2x80x2-biphenol can be prepared according to JP 85-216749. The3,3xe2x80x2-diaryl-substituted 1,1xe2x80x2-2-naphthols can be obtained according to J. Org. Chem., 1998, 63, 7536.
Phosphorochloridite may be prepared by a variety of methods known in the art, for example, see descriptions in Polymer, 1992, 33, 161; Inorganic Synthesis, 1966, 8, 68; U.S. Pat. No. 5,210,260; Z. Anorg. Allg. Chem., 1986, 535, 221. With ortho-substituted phenols, phosphorochloridites can be prepared in situ from PCl3 and the phenol. Also, phosphorochloridites of 1-naphthols can be prepared in situ from PCl3 and 1-naphthols in the presence of a base like triethylamine. Another process for preparing the phosphochlorodite comprises treatment of N,N-dialkyl diarylphosphoramidite with HCl. ClP(OMe)2 has been prepared in this manner, see Z. Naturforsch, 1972, 27B, 1429. Phosphorochloridites derived from substituted phenols have been prepared using this procedure as described in commonly assigned U.S. Pat. No. 5,821,378.
By contacting the thus obtained (OAr)2PCl, wherein Ar is a substituted aryl, with a divalent bridging compound, for example by the method described in U.S. Pat. No. 5,235,113, a bidentate phosphite ligand is obtained which can be used in the process according to the invention.
The transition metal may be any transition metal capable of carrying out catalytic transformations and may additionally contain labile ligands which are either displaced during the catalytic reaction, or take an active part in the catalytic transformation. Any of the transition metals may be considered in this regard. The preferred metals are those comprising group VIII of the Periodic Table. The preferred metals for hydroformylation are rhodium, cobalt, iridium, ruthenium, palladium and platinum. The preferred metals for hydrocyanation and/or isomerization are nickel, cobalt, and palladium, and nickel is especially preferred for hydrocyanation.
The catalyst compositions of the invention are comprised of at least one multidentate phosphite ligand according to any one of formulae I, II and III and a transition metal. In embodiments of the invention, catalyst compositions useful for processes such as hydroformylation may have Group VIII compounds such as can be prepared or generated according to techniques well known in the art, as described, for example, WO 95 30680, U.S. Pat. No. 3,907,847, and J. Amer. Chem. Soc., 1993, 115, 2066. Examples of such suitable Group VIII metals are ruthenium, rhodium, and iridium. Suitable Group VIII metal compounds are hydrides, halides, organic acid salts, acetylacetonates, inorganic acid salts, oxides, carbonyl compounds and amine compounds of these metals. Examples of suitable Group VIII metal compounds are, for example, Ru3(CO)12, Ru(NO3)2, RuCl3(Ph3P)3, Ru(acac)3, Ir4(CO)12, IrSO4, RhCl3, Rh(NO3)3, Rh(OAc)3, Rh2O3, Rh(acac)(CO)2, [Rh(OAc)(COD)]2, Rh4(CO)12, Rh6(CO)16, RhH(CO)(Ph3P)3, [Rh(OAc)(CO)2]2, and [RhCl(COD)]2 (wherein xe2x80x9cacacxe2x80x9d is an acetylacetonate group; xe2x80x9cOAcxe2x80x9d is an acetyl group; xe2x80x9cCODxe2x80x9d is 1,5-cyclooctadiene; and xe2x80x9cPhxe2x80x9d is a phenyl group). However, it should be noted that the Group VIII metal compounds are not necessarily limited to the above listed compounds. The Group VIII metal is preferably rhodium. Rhodium compounds that contain ligands which can be displaced by the multidentate phosphites are a preferred source of rhodium. Examples of such preferred rhodium compounds are Rh(CO)2 (acetylacetonate), Rh(CO)2(C4H9COCHCO-t-C4H9), Rh2O3, Rh4(CO)12, Rh6(CO)16, Rh(O2CCH3)2, and Rh(2-ethylhexanoate). Rhodium supported on carbon may also be used in this respect.
Nickel compounds can be prepared or generated according to techniques well known in the art, as described, for example, in U.S. Pat. Nos. 3,496,217; 3,631,191; 3,846,461; 3,847,959; and 3,903,120, which are incorporated herein by reference. Zero-valent nickel compounds that contain ligands which can be displaced by the organophosphorus ligand are a preferred source of nickel. Two such preferred zero-valent nickel compounds are Ni(COD)2 (COD is 1,5-cyclooctadiene) and Ni{P(O-o-C6H4CH3)3}2(C2H4), both of which are known in the art. Alternatively, divalent nickel compounds may be combined with a reducing agent, to serve as a source of nickel in the reaction. Suitable divalent nickel compounds include compounds of the formula NiY2 where Y is halide, carboxylate, or acetylacetonate. Suitable reducing agents include metal borohydrides, metal aluminum hydrides, metal alkyls, Zn, Fe, Al, Na, or H2. Elemental nickel, preferably nickel powder, when combined with a halogenated catalyst, as described in U.S. Pat. No. 3,903,120, is also a suitable source of zero-valent nickel.
Depending upon the desired reaction to be performed, the catalyst composition of this invention may also include the presence of one or more Lewis acid promoters, which affect both the activity and the selectivity of the catalyst system. The promoter may be an inorganic or organometallic compound in which the at least one of the elements of said inorganic or organometallic compound is selected from scandium, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, boron, aluminum, yttrium, zirconium, niobium, molybdenum, cadmium, rhenium and tin. Examples include ZnBr2, ZnI2, ZnCl2, ZnSO4, CuCl2, CuCl, Cu(O3SCF3)2, CoCl2, CoI2, FeI2, FeCl3, FeCl2, FeCl2(TBF)2, TiCl4(THF)2, TiCl4, TiCl3, ClTi(OiPr)3, MnCl2, ScCl3, AlCl3, (C8H17)AlCl2, (C8H17)2AlCl, (iso-C4H9)2AlCl, Ph2AlCl, PhAlC2, ReCl5, ZrCl4, NbCl5, VCl3, CrCl2, MoCl5, YCl3, CdCl2, LaCl3, Er(O3SCF3)3, Yb(O2CCF3)3, SmCl3, B(C6H5)3, TaCl5. Suitable promoters are further described in U.S. Pat. Nos. 3,496,217; 3,496,218; and 4,774,353. These include metal salts (such as ZnCl2, CoI2, and SnCl2), and organometallic compounds (such as RAlCl2, R3SnO3SCF3, and R3B, where R is an alkyl or aryl group). U.S. Pat. No. 4,874,884 describes how synergistic combinations of promoters can be chosen to increase the catalytic activity of the catalyst system. Preferred promoters include CdCl2, FeCl2, ZnCl2, B(C6H5)3, and (C6H5)3SnX, where Xxe2x95x90CF3SO3, CH3C6H5SO3, or (C6H5)3BCN. The mole ratio of promoter to nickel present in the reaction can be within the range of about 1:16to about 50:1.
The present invention provides for a process of hydrocyanation, comprising reacting an unsaturated compound with a source of hydrogen cyanide in the presence of a catalyst composition comprising a transition metal selected from Ni, Co, and Pd, and a Lewis acid compound, and at least one ligand selected from the group represented by formulae I, II, or III. Representative ethylenically unsaturated compounds which are useful in the hydrocyanation process of this invention are shown in Formulae IV or V, and the corresponding terminal nitrile compounds produced are illustrated by Formulae IV or VI, respectively, wherein like reference characters have same meaning. 
wherein
R22 is H, CN, CO2R23, or perfluoroalkyl;
y is an integer of 0 to 12;
x is an integer of 0 to 12 when R22 is H, CO2R23 or perfluoroalkyl;
x is an integer of 1 to 12 when R22 is CN; and
R23 is C1 to C12 alkyl, or aryl.
The nonconjugated acyclic, aliphatic, monoethylenically unsaturated starting materials useful in this invention include unsaturated organic compounds containing from 2 to approximnately 30 carbon atoms. Suitable unsaturated compounds include unsubstituted hydrocarbons as well as hydrocarbons substituted with groups which do not attack the catalyst, such as cyano. Examples of these monoethylenically unsaturated compounds include ethylene, propylene, 1-butene, 2-pentene, 2-hexene, etc., nonconjugated diethylenically unsaturated compounds such as allene, substituted compounds such as 3-pentenenitrile, 4-pentenenitrile, methyl pent-3-enoate, and ethylenically unsaturated compounds having perfluoroalyl substituents such as, for example, CzF2z+1, where z is an integer of up to 20. The monoethylenically unsaturated compounds may also be conjugated to an ester group such as methyl pent-2-enoate. Preferred are nonconjugated linear alkenes, nonconjugated linear Allen-nitriles, nonconjugated linear alkenoates, linear alk-2-enoates and perfluoroalkyl ethylenes. Most preferred substrates include 3- and 4-pentenenitrile, alkyl 2-, 3-, and 4-pentenoates, and CzF2z+1CHxe2x95x90CH2 (where z is 1 to 12).
3-Pentenenitrile and 4-pentenenitrile are especially preferred. As a practical matter, when the nonconjugated acyclic aliphatic monoethylenically unsaturated compounds are used in accordance with this invention, up to about 10% by weight of the monoethylenically unsaturated compound may be present in the form of a conjugated isomer, which itself may undergo hydrocyanation. For example, when 3-pentenenitrile is used, as much as 10% by weight thereof may be 2-pentenenitrile. (As used herein, the term xe2x80x9cpentenenitrilexe2x80x9d is intended to be identical with xe2x80x9ccyanobutenexe2x80x9d).
The preferred products are terminal alkanenitriles, linear dicyanoalkylenes, linear aliphatic cyanoesters, and 3-(perfluoroalkyl) propionitrile. Most preferred products are adiponitrile, alkyl 5-cyanovalerate, and CzF2z+1CH2CH2CN, where z is 1 to 12.
The present hydrocyanation process may be carried out, for example, by charging a reactor with the reactants, catalyst composition, and solvent, if any; but preferably, the hydrogen cyanide is added slowly to the mixture of the other components of the reaction. Hydrogen cyanide may be delivered as a liquid or as a vapor to the reaction. Another suitable technique is to charge the reactor with the catalyst and the solvent to be used, and feed both the unsaturated compound and the HCN slowly to the reaction mixture. The molar ratio of unsaturated compound to catalyst can be varied from about 10:1 to about 2000:1.
Preferably, the reaction medium is agitated, for example, by stirring or shaking. The reaction product can be recovered by conventional techniques such as, for example, by distillation. The reaction may be run either batchwise or in a continuous manner.
The hydrocyanation reaction can be carried out with or without a solvent. The solvent, if used, should be liquid at the reaction temperature and pressure and inert towards the unsaturated compound and the catalyst. Suitable solvents include hydrocarbons, such as benzene or xylene, and nitrites, such as acetonitrile or benzonitrile. In some cases, the unsaturated compound to be hydrocyanated may itself serve as the solvent.
The exact temperature is dependent to a certain extent on the particular catalyst being used, the particular unsaturated compound being used and the desired rate. Normally, temperatures of from xe2x88x9225xc2x0 C. to 200xc2x0 C. can be used, the range of 0xc2x0 C. to 150xc2x0 C. being preferred.
Atmospheric pressure is satisfactory for carrying out the present invention and hence pressures of from about 0.05 to 10 atmospheres (50.6 to 1013 kPa) are preferred. Higher pressures, up to 10,000 kPa or more, can be used, if desired, but any benefit that may be obtained thereby would probably not justify the increased cost of such operations.
HCN can be introduced to the reaction as a vapor or liquid. As an alternative, a cyanohydrin can be used as the source of HCN. See, for example, U.S. Pat. No. 3,655,723.
The process of this invention is carried out in the presence of one or more Lewis acid promoters which affect both the activity and the selectivity of the catalyst system. The promoter may be an inorganic or organometallic compound in which the in which the at least one of the elements of said inorganic or organometallic compound is selected from scandium, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, boron, aluminum, yttrium, zirconium, niobiumn, molybdenum, cadmium, rhenium and tin. Examples include ZnBr2, ZnI2, ZnCl2, ZnSO4, CuCl2, CuCl, CU(O3SCF3)2, CoCl2, CoI2, FeI2, FeCl3, FeCl2, FeCl2(THF)2, TiCl4(THF)2, TiCl4, TiCl3, ClTi(OiPr)3, MnCl2, ScCl3, AlCl3, (C8H17)AlCl2, (C8H17)2AlCl, (iso-C4H9)2AlCl, Ph2AlCl, PhAlCl2, ReCl5, ZrCl4, NbCl5, VCl3, CrCl2, MoCl5, YCl3, CdCl2, LaCl3, Er(O3SCF3)3, Yb(O2CCF3)3, SmCl3, B(C6H5)3, TaCl5. Suitable promoters are further described in U.S. Pat. Nos. 3,496,217; 3,496,218; and 4,774,353. These include metal salts (such as ZnCl2, CoI2, and SnCl2), and organometallic compounds (such as RAlCl2, R3SnO3SCF3, and R3B, where R is an alkyl or aryl group). U.S. Pat. No. 4,874,884 describes how synergistic combinations of promoters can be chosen to increase the catalytic activity of the catalyst system. Preferred promoters include CdCl2, FeCl2, ZnCl2, B(C6H5)3, and (C6H5)3SnX where Xxe2x95x90CF3SO3, CH3C6H5SO3, or (C6H5)3BCN. The mole ratio of promoter to nickel present in the reaction can be within the range of about 1:16 to about 50:1.
The invention will now be illustrated by the following non-limiting examples of certain embodiments thereof, wherein all parts, proportions, and percentages are by weight, unless otherwise indicated.
The following definitions are applicable wherever the defined terms appear in this specification:
The term xe2x80x9chydrocarbylxe2x80x9d designates a hydrocarbon molecule from which one hydrogen atom has been removed. Such molecules can contain single, double or triple bonds.
3PN: 3-pentenenitrile
2PN: 2-pentenenitrile
4PN: 4-pentenenitrile
2M3: 2-methyl-3-butenenitrile
VN: valeronitrile
ESN: ethylsuccinonitrile
MGN: 2-methylglutaronitrile
5FVN: 5-formylvaleronitrile
M3P: methyl 3-pentenoate
BD: 1,3-butadiene
COD: 1,5-cyclooctadiene
Et3N: triethylamine
PCl3: phosphorus trichloride
THF: tetrahydrofuran
The protocol for calculating certain reaction results for hydrocyanation reactions and isomerization reactions follows:
For step 1 hydrocyanation reactions the % useful pentenenitriles (PN""s) and the 3PN/2M3 ratio is reported. The product distribution is analyzed by gas chromatograph using valeronitrile as an internal standard. The % usefil PN""s is the molar ratio of the sum of 3PN(cis and trans) and 2M3 divided by the amount of HCN. The 3PN/2M3 ratio is the ratio of cis and trans 3PN to 2M3.
For step 2 hydrocyanation reactions the selectivity to adiponitrile (ADN) is ADN/(ESN+MGN+ADN). The 3PN and 4PN conversion is calculated using 2-ethoxyethylether (EEE) as an internal standard. The total conversion of pentenenitriles (PN""s) to dinitriles (DN""s), based on the assumption that all material is accounted for, is calculated as (sum (mol DN""s)/sum (PN""s+BN""s+DN""s)). (BN""s are butenenitriles). The conversion based on HCN is calculated by dividing the total conversion of PN""s to DN""s by the HCN/PN ratio in the original feed, i.e., (mol DN/mol PN at sart)/(mol HCN/mol PN at start).